Body-coupled communications (BCC) or body-based communication has been proposed as a basis for body area networks (BANs) as standardized by the 802.15.6 Task Group of the Institute of Electrical and Electronics Engineers (IEEE). BCC allows exchange of information between a plurality of devices which are at or in close proximity of a body of a human or an animal. This can be achieved by capacitive or galvanic coupling of low-energy electric fields onto the body surface.
In body-coupled communication (BCC) systems information is transmitted from a transmission device to a receiver device via signals across the user's body. Body-coupled communication may utilize an electric field to transmit information. Body-coupled communication (BCC) uses the human body as communication channel. It enables wireless communication over a human body between devices that are in contact with that human body. Signals are conveyed over the body instead of through the air. As such, the communication is confined to an area close to the body. Therefore, communication is possible between devices situated on, connected to, or placed close to the body.
In body-coupled communication (BCC) the signals are transmitted via couplers, which are placed near or on the body. These couplers transfer the data signal, for example galvanically or capacitively, to the body. The transfer characteristic of the body channel is shown to be good for frequencies from about 100 kHz up to about 100 MHz. The noise is highest at low frequency and declines with 1st to 3rd order roll-off depending on the environment. Lower frequencies may thus be more affected by electrostatic interference in the body channel. At frequencies above 100 MHz the wavelength, i.e. <3 m, comes in the range of the length of (parts of) the human body, and the human body starts to act as an antenna; as a consequence, it is possible that the BCC nodes located on different bodies can communicate which each other using the “human body antenna”. For even higher frequencies, even the couplers start acting as antennas. Hence, communications could also take place when the (human) body is not present as communication medium. Both effects are unwanted, since only devices placed on or near the same (human) body are supposed to communicate.
It has been proposed to use a half-duplex methodology where there are alternating transmit and receive cycles. This is so the transmission does not affect the receiver performance.
In some applications, it may be desirable to have a device which is able to transmit and receive during a same clock cycle.